The use of a plurality of different shaped cushions which can be juxtaposed to provide support surfaces with different configurations is described for example in the following U.S. patent references, the disclosures of which are hereby incorporated by reference herein:    U.S. Pat. No. 6,925,669 B1;    U.S. Pat. No. 4,905,330;    U.S. Pat. No. 4,473,913; and,    U.S. Pat. No. 4,171,549.
A problem with such devices is that cushions by their nature tend to be bulky which causes storage issues when they are not being deployed.